The present invention relates to a method of adjusting the position of a stencil relative to a printing table, and in particularly relative to a reference pattern applied to the printing table, and apparatus for carrying out the method.
In silkscreen printing machines, the stencil with associated frame is fixed relative to the stand of the silkscreen printing machine. The printing table, which may be reciprocatingly movable, is also fixed relative to the stand of the printing machine.
In silkscreen printing machines it is a prime desire that the pattern assigned to the stencil be precisely positioned in relation to the material fixedly oriented to the printing table via registering means. It is practically always necessary to adjust the stencil (or the printing table) before the pattern obtains its exact position on the material. This adjustment has been found to be complicated and, above all, time consuming.
For the purpose of adjustment, it is previously known to apply a reference material to the registering means of the printing table and then move the printing table to the printing position and thereafter to apply the stencil pattern to the reference material. When the reference material is again moved back to the infeed position, it is possible to establish whether the stencil pattern deviates from the desired position, i.e. the pattern of the reference material, and if so by how much. In order to compensate for this deviation it is necessary to adjust the stencil pattern in relation to the material, since the material is fixedly related to the registering means with reference to a special position on the printing table.
In order to enable the stencil pattern to be adjusted, it has previously been proposed to hold the stencil in a first frame which, in turn, is held by but rotatably and displaceably arranged in a further frame. This further frame is fixed relative to the machine stand.
When a deviation has been established, it is necessary to adjust the first frame of the stencil relative to the other frame, this being effected by means of a plurality of setting devices. The setting devices are activated, however, "by instinct" and are set to such values that the stencil pattern can be assumed to be placed exactly on the material. Subsequent to actuating the setting devices, a further print is made on a reference material to establish whether the setting approaches the desired exact setting or not. This setting work has been found extremely complicated, perhaps primarily because the setting is not only oriented in the "x" and "y" direction, i.e. at right angle coordinates, but normally requires the stencil to be twisted.